Second touch Keyboard

If you have a real second touch keyboard with separate key contacts you can present it with an ordinary keyboard element in jOrgan.
But even without an additional hardware you can simulate a second touch on a single wikipedia:Midi device:

Velocity

If you limit the PressKey and ReleaseKey messages to a certain velocity range, you can control to which key presses the keyboard will react. This won't give you the exact feeling of second touch on a real organ though.